title: Trends in computed tomography utilization rates: a longitudinal practice-based study.
abstract: OBJECTIVE
  Computed tomography (CT) use has increased dramatically over the past 2 decades, leading to increased radiation exposure at the population level. We assessed trends in CT use in a primary care (PC) population from 2000 to 2010.
  
  
  METHODS
  Trends in CT use from 2000 to 2010 were assessed in an integrated, multi-specialty group practice. Administrative data were used to identify patients associated with a specific primary care provider and all CT imaging procedures. Utilization rates per 1000 patients and CT rates by type and medical specialty were calculated.
  
  
  RESULTS
  Of 179,032 PC patients, 55,683 (31%) underwent CT. Mean age (SD) was 31.0 (23.6) years; 53% were female patients. In 2000, 178.5 CT scans per 1000 PC patients were performed, increasing to 195.9 in 2010 (10% absolute increase, P = 0.01). Although utilization rates across the 10-year period remained stable, emergency department (ED) CT examinations rose from 41.1 per 1000 in 2000 to 74.4 per 1000 in 2010 (81% absolute increase, P < 0.01). CT abdomen accounted for more than 50% of all CTs performed, followed by CT other (19%; included scans of the spine, extremities, neck and sinuses), CT chest (16%), and CT head (14%). Top diagnostic CT categories among those undergoing CT were abdominal pain, lower respiratory disease, and headache.
  
  
  CONCLUSIONS
  Although utilization rates across the 10-year period remained stable, CT use in the ED substantially increased. CT abdomen and CT chest were the two most common studies performed and are potential targets for interventions to improve the appropriateness of CT use.
authors.affiliation: From the *Department of Emergency Medicine, Division of Emergency Medicine Research, †Knowledge and Evaluation Research Unit, ‡Department of Health Sciences, Division of Health Care Policy and Research, §Department of Internal Medicine, Division of Primary Care Internal Medicine, Mayo Clinic, Rochester, Minnesota; ∥Texas Medical Institute of Technology, Austin, Texas; and ¶Department of Radiology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Erik P
authors.initials: EP
authors.lastname: Hess
authors.forename: Lindsey R
authors.initials: LR
authors.lastname: Haas
authors.forename: Nilay D
authors.initials: ND
authors.lastname: Shah
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Stroebel
authors.forename: Charles R
authors.initials: CR
authors.lastname: Denham
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Swensen
mesh_terms: D000328:Adult; D000368:Aged; D015984:Causality; D015897:Comorbidity; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010818:Practice Patterns, Physicians' / Q000639:trends*; D011320:Primary Health Care / Q000706:statistics & numerical data / Q000639:trends*; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000453:epidemiology*; D011835:Radiation Protection / Q000706:statistics & numerical data; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data* / Q000639:trends*; D014600:Utilization Review